Wireless Communication System, Control Server, and Base-Station Switching Operation Control Method

1. A wireless communication system including an on-board terminal equipment mounted on a working machine, which travels along a predetermined travel route in a mine, and a control server, which manages operation of the working machine, communicably connected together via a network including a first wireless base station and a second wireless base station, wherein: the control server comprises: a travel-permitted region setting unit that for the working machine, sets a region in the travel route, for which a travel permission has been given only to the working machine, as a travel-permitted region and generates permission response information including position information of the travel-permitted region, a no-handover zone setting unit that sets a travel permission requesting zone in the travel-permitted region, in which zone, the working machine makes a setting request to the control server for setting a new travel-permitted zone as a no-handover zone in which switching of a connected base station from the first wireless base station to the second wireless base station is prohibited, a switching operation control unit that generates switching operation control information for allowing the working machine to perform switching of the connected base station outside the no-handover zone, and a server-side communication control unit that transmits the switching operation control information to the working machine; and the on-board terminal equipment comprises: a terminal-side communication control unit that receives the switching operation control information, and based on the switching operation control information, switches the connected wireless base station in a zone other than the no-handover zone, and transmits, to the control server, permission request information for making a setting request for the new travel-permitted zone.

2. The wireless communication system according to claim 1 , wherein: the control server includes, as the switching operation control unit, a handover map information generating unit that generates provisional handover map information, which provisionally sets a communication area of the first wireless base station and a communication area of the second wireless base station, based on data communication quality of a communication area of the first wireless base station and data communication quality of a communication area of the second wireless base station and, if a boundary between the communication area of the first wireless base station and the communication area of the second wireless base station and the no-handover zone overlap each other, corrects the provisional handover map information so as to place the boundary outside the no-handover zone, and generates corrected handover map information, the server-side communication control unit transmits the corrected handover map information as the switching operation control information to the on-board terminal equipment, and the terminal-side communication control unit receives the corrected handover map information, acquires, from a position calculating device mounted on the working machine, position information of an own vehicle during operation of the working machine, and, if the wireless base station having the communication area corresponding to the position of the own vehicle in the corrected handover map information and the wireless base station set as the connected base station by the terminal-side communication control unit are different, switches the connected wireless base station to the wireless base station corresponding to the position of the own vehicle.

3. The wireless communication system according to claim 2 , wherein: the handover map information generating unit performs the correction based on at least one of an index value indicating data communication quality in the no-handover zone, a result of a comparison between a distance from the travel-permitted zone to the first wireless base station and a distance from the travel-permitted zone to the second wireless base station, and a result of a comparison between a size of the communication area of the first wireless base station, the communication area of the first wireless base station occupying the travel-permitted zone, and a size of the communication area of the second wireless base station, the communication area of the second wireless base station occupying the travel-permitted zone.

4. The wireless communication system according to claim 1 , wherein: the control server includes, as the switching operation control unit, a handover map information generating unit and a handover necessity determination unit for determining necessity of switching of the connected wireless base station in the on-board terminal equipment, the handover map information generating unit generating provisional handover map information, which provisionally sets a communication area of the first wireless base station and a communication area of the second wireless base station, based on data communication quality of the communication area of the first wireless base station and data communication quality of the communication area of the second wireless base station and, if a boundary between the communication area of the first wireless base station and the communication area of the second wireless base station and the no-handover zone overlap each other, correcting the provisional handover map information so as to place the boundary outside the no-handover zone, and generating corrected handover map information, the terminal-side communication control unit acquires position information of an own vehicle from a position calculating device mounted on the working machine, and transmits, to the control server, the position information of the own vehicle and base station identification information that specifically indicates the wireless base station currently set as the connected base station, the handover necessity determination unit, if the wireless base station corresponding to the communication area, which includes the position of the own vehicle, in the corrected handover map information and the wireless base station indicated by the base station identification information are not the same, determines that switching of the connected wireless base station is needed, and generates switching command information for allowing the on-board terminal equipment to switch the connected wireless base station, the server-side communication control unit transmits the switching command information as the switching operation control information, and the terminal-side communication control unit switches the connected wireless base station according to the switching command information.

5. The wireless communication system according to claim 1 , wherein: the control server includes, as the switching operation control unit, a handover map information generating unit that generates handover map information, which sets a communication area of the first wireless base station and a communication area of the second wireless base station, based on data communication quality of the communication area of the first wireless base station and data communication quality of the communication area of the second wireless base station, the server-side communication control unit transmits the handover map information and no-handover zone information, which indicates the no-handover zone, as the switching operation control information to the on-board terminal equipment, and the terminal-side communication control unit acquires, from a position calculating device mounted on the working machine, position information of an own vehicle, compares the no-handover zone information and the position information of the own vehicle with each other, and, if the position of the own vehicle is not included in the no-handover zone and the current connected wireless base station is not the same as the wireless base station corresponding to the communication area that includes the position of the own vehicle in the handover map information, switches the connected wireless base station.

6. The wireless communication system according to claim 1 , wherein: the travel route is connected to at least one of a loading site, where a payload is loaded on the working machine, and a dumping site where the working machine dumps the payload, and the no-handover zone setting unit further sets, as the no-handover zone, an inside of the loading site and an inside of the dumping site.

7. The wireless communication system according to claim 1 , wherein: the no-handover zone is defined as a closed zone in the mine.

8. A control server communicably connected to an on-board terminal equipment mounted on a working machine, which travels along a predetermined travel route in a mine, via a network including a first wireless base station and a second wireless base station, whereby the control server manages operation of the working machine, which comprises: a travel-permitted zone setting unit that for the working machine, sets a region in the travel route, for which a travel permission has been given only to the working machine, as a travel-permitted zone and generates permission response information including position information of the travel-permitted zone, a no-handover zone setting unit that sets a travel permission requesting zone in the travel-permitted region, in which zone, the working machine makes a setting request to the control server for setting a new travel-permitted zone as a no-handover zone in which switching of a connected base station from the first wireless base station to the second wireless base station is prohibited, a switching operation control unit that generates switching operation control information for allowing the working machine to perform switching of the connected base station outside the no-handover zone, and a server-side communication control unit that transmits the switching operation control information to the working machine.

9. A base-station switching operation control method for controlling switching operation of a base station in an on-board terminal equipment mounted on a working machine, which travels along a predetermined travel route in a mine, in a wireless communication system including the on-board terminal equipment and a control server, which manages operation of the working machine, communicably connected together via a network including a first wireless base station and a second wireless base station, which comprises the following steps: setting, for the working machine, a zone in the travel route, for which a travel permission has been given only to the working machine, as a travel-permitted zone, setting, as a no-handover zone in the travel-permitted zone, in which switching of a connected base station from the first wireless base station to the second wireless base station is prohibited, a permission requesting zone, in which the working machine makes a setting request to the control server for a new travel-permitted zone, generating switching operation control information for allowing the working machine to perform switching of the connected base station outside the no-handover zone, transmitting the switching operation control information to the working machine, and allowing the working machine to switch the connected wireless base station according to the switching operation control information.